Telephony.



M. L. JOHNSON.

TELEPHONY.

APPLICATION FILED AUG.10,1911.

Patented July 28, 1914.

3 SHEETSSHI2ET 1.

N -m ma ML. Wm T m n ATTOR/VE Y M. L. JOHNSON.

TELEPHONY.

APPLICATION FILED AUG.10, 1911.

Patented July 28, 1914.

l/Vl/E/VTOR MORTON L JOHNSON ATTORNE Y M. L. JOHNSON.

TELEPHONY.

APPLICATION FILED AUG. 10, 1911.

Patented July 28, 1914.

3 SHEETS SHEBT 3.

INVENTOR HORTON. L.JOHNSOI\L ATTOR/VE V UNITED STATES PATE TOFFIC MORTON JOHNSON, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO FRAN B. COOK COMPANY, OF CHICAGQILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONY.

Specification of Letters Patent.

. Patented July 28, 1914.

' Application filed August 10, 1911. Serial No. 643,336.

To all whom it may concern:

Be it known that I, MORTON L. JorINsoN, a citizen of the Uni-ted States, residing at Chicago, in the county of Cook and State of my invention is'of special utility in connec- .tion with private branch exchanges though it is not to be limited to, this use.

In practising my invention I preferably employ as many llIlk connectors as are required to take care of the busy hour of the exchange. Each ofthese link connectors has a plurality of connecting switches, prefer ably but one-for each line centering at the exchange. \Vher'e a single switch r each line per link connector is employed such switch is desirably capable of effecting the operators telephone connection'with the line to which such switch is individual, when such line is a calling line, and which is capable of effecting the association of a.

source of ringing or signaling current with the line to which it is individual, when such line is a called line.

The telephone exchange system of my invention preferably includes means whereby a link connector is limited to telephonic connection with two telephone lines at a time.

This feature of my invention is desirably embodied-an an equipment by" which all switches of .a link connector that is "einloyed tor connecting two lines in conversaion, except the two switches that enable this link connector to perform its function,'are

mechanically prevented fromefl'ecting connection of their lines: withsuch vlink connector when already in service'in connecting a callin and called lin'e, though I do not dc sire to ie limited to the preventionfof the operation of switches for this purpose.

My invention has for a further object the provision" of means whereby the intrusion of an operator into an established circuit is uarded against to prevent the operator *rom listening in, whereby the system of my invention is rendered secret, though I do not limit myself to this characteristic. As I have organized my invention I"mechani-- cally prevent-the inclusion of an operators telephone in connection with a link that is serving to connect two lines and'I further employ means for electrically preventing the effective connection, of an operators telephone with two-connected lines-when the operator seeks to effect the connection of her telephone with suchtwo connected lines with i the aid'of. two link connectors. In the first telephone in an established connection jointly serve to prevent such connection of, the operato-rs telephone 1 do not Wish'to, be limited, however, to'themechanical and clectrlcal means, as specified,.foripreventing the association of the 'operators telephone with an established connection.

In accordance with another feature, of my invention I provide supplemental listening keysindiVidual to the. telephone lines and provi'de means whereby none of these listening keys may be operated to include an operators telephone incircuit with connectedlines." The system of my invnt-ionalso in-' cludes meansto preventa third. line from becoming connected in anyway with connected lines.

There are other objects and advantages of my invention which I- will not set" forth in this introductionbut which. will more fully panying drawings in which-' 1 appear-by reference to a preferred embodi i .ment of my invention shown in. the accom- Figures 1 and 2 collectively-constitute a diagrammatic illustration of a system equipped in accordance with the invention,

the right hand. end of Fig. 1 to. be; joined with the left hand end of Fig. 2 in reading these figures; Fig. 3 is a diagrammatic view illustrating mechanism for automatically effectingv the extension of a vtelephone line that may enter into the system of my inventiomthe line illustrated 1 being a well known automatic telephone line;.Fi'g. 4 is a plan view-of a portio yof switching mechanism which i prererably employ; Fig. 5 is an end View, somewhat diagrammatic, of switching mechanism which I preferably employ; Fig. 6 is a view similar to Fig. 5 except that the partsoccupy another position preparatory to their restoration to nor-;

mal; Fig. 7 is a view on line 7 7 of Fig. '5; and Fig. 8 is a side view of a manually operated restoring key.

Like parts are indicated by similar char acters of reference throughout the different figures.

In Figs. 1 and 2 I have shown three tele* phone lines that extend to the private branch exchange, one of these telephone lines being in the form of a trunk 1 extending from an other exchange diagrammatically indicated at 2 where one of many link connectors is illustrated for connecting the trunk line 1 with a telephone line extending to the exchange at 2, as for instance, from a substation A, all as is well known by those skilled in-the art, on which account the apparatus illustrated at 2 and A will not be specifically described. Another telephone line 3 is illustrated as extending from a manual exchange subscribers station B. A telephone line 4 extends from a manual exchange subscribers station C. The telephone line l-is shown as provided with two switching devices preferably in the form of keys 5 5, two keys being shown as there are but two link connectors shown as will appear, each key 5 being individual to a link connector. The telephone line 3 is provided with two keys 6 individual to said link connectors and the telephone line at is provided with keys 7 individual to the link connectors. One of the link connectors proper includes the two talking strands 8 8. The other of the two illustrated link connectors includes the talking strands 9 9. The keys 5, 6 and 7 each includes a pair of lever s irings 10 that are connected with the sides of the lines to which the keys of which springs 10 form parts are individual. The normally open contacts of the springs 10 of the keys 5, G, and 7 to which the link connector 8 is common are connected with the side of this link connector. The sides 9 of the remaining link connector are similarly connected with the normally open contacts of the lever springs 10 of the keys 5, 6, and 7 individual to this latter connector. Thus each line is. provided with a pair of contact springs 10 for each link connector and eachlink connector is provided with normally open contacts for the springs 10 of the keys associated thercwith. By depressing keys associated with the same link connector, lines individual to said keys may be connected.

Let it be assumed that station A is a. calling station and that the trunk line No. it becomes, indirectly, a calling line. Let it also beassumed that the station C happens to be the called station and the line 4 thereof the called line. The operator at exchange 2, in a well known way, efiects the operation of a line signal 11. The operator at the private branch exchange where the keys 5 (3, and 7 are located depresses a key 5 individual to the calling-line 1 and which is associated with an idle link connector 8, the extent to which the key is depressed being sutiicient to enable said key to rock the trip 12 tea position in which it may escape the cam 13 and occupy a position above said cam to hold the depressed key in a position in which the sides of the line 1 will be connected with the sides 8 of the selected link connector through the intermediation of the contact springs 10 and the contacts provided for said springs. The portion 1-1 of the depressed key moves a bar 15 against the force of the bar restoring spring 15 in the plane of the bar to cause the pawl 16 to move the toothed wheel 17 one step to the right from the normal position of said toothed wheel (which normal position is shown at the lower one of the two wheels 17 in Fig. 2). The wheel 17 is fixed upon ashaft 18 that carries a cam 19. Upon the single step in the rotation of the shaft 18 accomplished by the depression of the actuated key 5, the cam 15) is caused to bring the springs 20 into engagement with their contacts which normally constitute the terminals of the operators telephone outfit 21, the operators telephone being bridged across the sides of the calling line 1 as a consequence of the engagement of the springs 20 with their contacts whereby the operator is informed of the wants of the calling subscriber. Assuming that the calling subscriber desires connection with sta-- tion G, the operator will fully depress the key 7 associated with the selected link coir nector 8 'and individual to the line 4 of the party to be called. The cam L1- will again operate the bar 15 to move the previously actuated star wheel 17 another step to remove the cam 19 from engagement with the spring mechanism 20 thereby to remove the springs 20 from their contacts to cut the operators telephone out of circuit. \Vhen the key 7 individual to the called line has been fully depressed, the ringing circuit con tacts 22 are closed to establish circuit through the ringing magnet 23, which circuit. may be traced from that contact 22 which is directly grounded to the remaining contact 22, the winding of ringing magnet 23, the l'vattery 2-.t to ground. The armature switches of magnet 23 are thereupon withdrawn from engagement with the normal Contacts and are brought into engagement with the alternate contacts which are connected with the terminals of an alternating current generator llach oi the lines of stations 13 and C has a ringing magnet 2-), the sides of these. lines memes I being connected with the armature Switches of said magnet so that when said magnets are energized in the manner which has been described the generator is included in circuit with the called line thereby to operate the signal receiver 20 at the station of the called line. Assuming that the actuated key 7 individual to the called line 4 is still fully depressed, acircuit is also established which may be traced from the grounded battery 27, which may be the same battery 24 made common, through the resistance 28, the then engaged contacts 29, the marginal relay (provided for a purpose to be stated) the cut off relay 31 to ground, The armature switches of the cut oil relay 31 are thus disengaged from their contacts that lead, one,

direct to ground and the other to ground through a battery 32" (which may be the same battery 24 made common with the batteries 27 and 32). .The cut oil' relay 31 of the called linep4when energized as described and shown, interrupts the circuit for the line signal 33 andprevents the operation of the signal33 byway of the armature switches of cutofl' relay 31 when the party C responds. The battery circuitfor the signal 33 includes the employed link connector and the battery 34 whereby the signal 33 acts as a supervisory signal to determine when the called party responds. The battery 32 is only adapted to enter iz'e relay 33 as a line signal. As illustrated t e signalsf33 of the lines'3 and 4 serve not only to enable the stations B, O to'initiate' calls buta'lso serve to indicate to"the"operato'r that these stations have responded when they are called, and serve further to indicate to the operator that the partiesat stations B, C have restored their telephones upon their switch hooks. That is, the signals 33: are not only line signals but are supervisory or disconnect signals as 'well.

The circuit connections for the signal that are no'rmally'furnished at the associate i2 cutoff relay 31 arereplace'd, where the trunk line is a calling line, by connections including the common battery 34 at the exchange 2, this batterybeing in bridgeof the sides 1; of the trunk line and thereby being in bridgeof'the sides 8 of the employed link connecton and through-these sides 8 in" bridgebetweenthe sidesof the called line 4.'-

If the station B were the callingstat-ion,"

the normal connections furnished for the signal 33 of the called line at. the cutofl' relay would be replaced by the battery 35 (which could be merged withthe batteries indicated at 24, 27 and this battery 35 bein included in circuit with the signal 33 by .a path which may be traced from the upper terminal of the battery 35, the winding of the relay 36, the uppermostarmature switch of the relay 37 and the then engaged contact of such armature switch, the normally engaged contacts 38 of a key- 39, a side 8 of the gized as a. supervisory signal.

called line.

employed link connector, the right hand spring 10 and its then engaged contact, one side of the line 4, the normally engaged contacts 40 of a listening key to be later described, the right hand armature switch of the ringing magnet 23 and its normal contact, one side of the line 4, the signal 33, the telephone equipment at the substation C, the other side of the line 4, the left hand armature switch of the ringing magnet 23, the normallyengaged contacts 41 of the aforesaid listening key, the left hand spring 10 of the selected key 7 associated with the link connector 8, the normally engaged contacts 42 Qf'the key 39, the lowermost armature switch of relay 37 and its normally engaged contact, the impedance coil 43 to ound. Assuming that the called party at station C who is connected by way ofthe trunk line hasresponded, the signal 33 will be ener- When the called party restores his telephone upon its switch hook, the high resistance bridge including the signal receiver 26 is substituted for the low resistance telephone bridge so that the signal receiver 33 is rendered inert, the signal device 33 thus acting fully to inform the operator of the condition of the Where a local line, such as either of the lines 3 and 4, is a callin line, the signal 33 will also serve to keep the op erator informed of the condition of such line, such signal, when energized, then receiving its current from the. battery 35. After the operator has fully depressed the key 7 with t e results which have been specified, she then releases said ke so that the cani 13 willbe engaged by t e trip 12 to hold the key 7 in the position shown in Fig.

2 during anestabl ished connection, the cam 13 escaping the trip 12 when the key 7 has been lowered to or toward itsringing position so that said tri -is in position to engage the cam 13 when t e key 7 is partially returned to its normal idle. position. understood that any 'keyindi'vidual to the line is depressed sufliciently to enable the cam 13 to escape the trip 1-2'but preferably not sufliciently to include the ringing generator in circuit with the calling line.

When the star wheel 17 has been turned two steps to disengage the springs '20 from their contacts, the holding" pawl 44 is moved bythe cam 45 to place it into engagement with a bar 46 to hold this bar in its normal position. Normally the bar 46 is free of the detent 44, this bar being provided with a recess 47 for each of the keys 5, 6 and 7, this recess It is' line 3 or the line 4 when such line is a calling V at each key being normally so positioned that the bar 46 Wlll be engaged by the cam 14 when such key is depressed to effect a slight movement of the bar 46 to the left 'agai ist the force of aspring 48, the normal n disconnection of the detent 4 -1 permitting the movement of the bar 46 by an engaging cam 14 and permitting the return movement of said bar by the spring 48. \Vhen. however, the bar 48 is locked in position by the detent 41. which occurs when two keys associated with said bar have been operated to connect' a calling; and called line, no further key associated withsaid bar can be depressed whereby no other line may be connected with lines previously connected and whereby the operators telephone set cannot be included in circuit with these previously connected lines, which could be done were she permitted to step the shaft 18 around farther.

I have now described how a calling part} secures connection with a called party and have specifically referred to apparatus as sociated with one of the lines which has been chosen to represent a calling line, and have specifically described apparatus associated with a line chosen to represent a called line. A large number of devices are illustrated having similar functions and possessing similar parts, and I Will therefore apply reference characters to similar parts of the equipment which have similar functions. In the case of the trunk keys 5, a slight distinction happens to exist, in the embodiment of the invention illustrated. as compared with the local line keys 6 and 7. The normally separated left hand contacts 49 are included in a circuit normally open at said contacts and which circuit ma be traced from the grounded battery 50 which may be merged with the batteries it. PT and 32, through the contacts 49. the grounded relay 51. the relays 51 and 30 being pro vided for similar purposes. each to be unresponsive when but one key of the line to which it is individual is actuated. 1f air other key, individual to such line. actuated then the flow of current through the relays 51 or 30 will be sulliciently increased to enable such relay to be energized to establish circuit at 5; to establish a sh rt circuit across the associate line wherclrv the voice currents are shunted so that no line may intrude, The contacts 53 ma, also be closed to operate an alarm S to notify some one in authority that the exchamg'e is not being properly ope ated. By the ward a l- Forded at 52 the operator is prevent-ml from using an idle link connector for 'otiilt'l ing her telephone set in circuit with an e tablishcd connection and from conn cting a third party in circuit with ar hcd connection. llach of the trunk ir u t 5 is provided with a pair o ll="t'lll'ili arated contacts 5.,- in a nci" tally open i cuit which may be traced "om a baticry so (that niav be lltcltl'ttl wi. l batterie :.l.

21352 and 3(1) the conta t 33, the condu tor 8 the windingof cutotl' relay 1%? to ground.

this cutofi' relay or being peculiar only to the trunk keys. lYhen the relay 3? is energized the battery 35 is removed to enable the use of the battery 3t free from other battery influence this battery 3 supplying the telephonic current in place of the battery :35 which is employed to supply such current when local lines are connected,

To preyent the operator from using keys of ditl'crent link connectors for bringing her telephone into circuit with a connection established by such link connectors 1 provide contacts 20 which are closed when the springs 30 engage their contacts. The coin tacts 90. when closed. establish circuit through the magnet 20 which circuit may be traced from the grounded terminal of said magnet through the engaged contacts 20 the normally engaged contacts 20. the resistance coil -30. and the grounded battery 30 The resistance of the magnet fit is such. htnvevcr. that it will not be clitl'iflZttl when but one pair of contacts '20 is closed but will be energized when two pairs of contacts 20. pertainin to the. keys that are actuated by the operator in the etfort to listen in. are closed, it is understood that when an operator thus employs two keys of dill'erent link connectors in an endeavor to listen in on an establi h d connection she will cause the star wheels 17 individual to such employed kcys to more each one step only from normal whereby conta i are, losed at 20 whereby the relay 20 will receive current supplied thereto through the two reristances Qt) that are in parallel with each other and in serial relation with the relay 9t) whereupon the relay Qt) will reccive sutlicicnt current to prevent the telcphonic connection of the operator's 01 in the established circuit, ls hcn the magnet -30 is energized a low resistance shunt is closed at its left hand armature switch across the sides ol the operators telephone unit. 'l'hi- 'bzint conncu-ti n joins springs :30 and ltcrcl prevents a third station from listening in :1 Wu an established connection by means of my circuits the perator may The right hand arma be able to establish. ture switch of the magnet 10* will. when said magnet is sutlicicntly energized as described. operate the signal ill for the purpose hitherto stated.

The trips 12 are. iivotally mounted at their elbows upon a common bar 57 which is provided for closing a pair ot contact 58 when the oar fii' is moved against the force of its rest ring swing Si) by 1hr ag' incnt of the can: )3 of an a tuated lf( .Jtl (ll cull'icd by the bar. this; ,inejcr HO be lug engaged by such cam 13 to maintain the clcs'ure of the contacts 58 until the parts are restoiad to n rn'ial. A suming that two 1 local lines ll('ll as tho e, of stations-'1) and (l l have been connected and are through the relay 36 will 'be denergized when the telephone receivers at both local stations are restored upon their switch hooks. The mag net 61, which was previously energized over a local circuit established by the relay 36, is included in open circuit so that its armature may engage its contact thereby to establish a circuit which may be traced from the grounded battery (32 through the armature switch and contact of relay 61, the magnet 63, the magnet 64, the contacts 58 to ground. The magnet 64 (thereupon withdraws the holding pawl 65 which is provided to maintain star wheel 17 in any position to which it is placed, whereupon the restoring spring 66 operates to restore the star wheel 17 and the shaft 18 to normal, this normal position being illustrated at the lower star wheel 17 in Fig. 2. The magnet (33 is in the association illustrated in Figs. 5, 6, and 7. lVhen it is energized its armature, which is in engagement with angular extensions of the bars 46, 15 and 57, rocks said bars away from the keys so that said keys may be thrust to their uppermost positions by the coil springs illustrated at the lower ends thereof, whereupon circuit is opened at 58 and the armature of magnet 63 is restored, the entire apparatus then being in normal position.

Where one of the lines is a trunk line I desirably provide a finger (37 upon the rod 57 so that circuit through a magnet 68 may be established by the closure of contacts 69 when the bar 57 is moved to the right. The armature 01' the magnet (38 maintains circuit through said magnet, which'circuit includes the sides of the trunk line 1, the battery 34 in bridge or said sides, portions of the sides of the link connector 8 and the relay (38, an other magnet 69 being serially included in a portion of one of the sides of the link connector in serial relation with the relay 68. The magnet (38 acts to maintain circuit for the magnet 69 and also serves to prevent a change, prior to the response of the called party, in the supervisory apparatus at the exchange 2, the magnet 68 being of sufficiently high resistance to enable it to be shunted by the called party's telephone so that the supervisory signal at the trunk end of the link connector at the calling exchange may be under the control of the telephone at the called station, the magnet 68 then being out of circuit. The circuit of the re lay (39 however, remains intact, a connection in place of that afforded by the armature switch of relay 68 being furnished by the switch hook and telephone bridge at the called station. The armature switch of relay (39 when attracted, serves to establish the circuit which may be traced from ground through said armature switch over conductor 3 through relay 61 and the grounded battery 62, with the result that the armature switch of the magnet 61 is attracted to hold the circuit through the magnets 63 and '64 open, the magnet 69, when associated with the trunk circuit, thus performing the func tion of the magnet 36 when this magnet 36 is associated with two connected local lines. \Vhen the circuit for the magnet 69 is opened, which is usually done at the called station by the restoration of the telephone receiver upon its switch hook, the magnet 61 is deenergized and the magnets 63 and 64 are energized with results which have been described.

\Vhen the trunk line 1 is automatically constituted a'continuation of a telephone line, as for example by the equipment illustrated in Fig. 3, the magnet 68 serves to prevent the premature release of the trunk line 1, the shunt which is established by the magnet 68 at its armature switch for this purpose being replaced by the low resistance bridge which is established at the called station, when the party at the called station responds.

A key 39 is individual to each link circuit, these keys being shown in normal position. The shanks of the keys pass through enlarged openings in the bars 15 and &6, these bars having no mechanical relation with said key. Each key 39 is provided with a cam 13 cooperating with the trip 12 similarly to the 9 cooperation of the other cams 13 with the trip 12 associated therewith. The keys 39 enable the operator to exclude her telephone set from circuit with a calling line without connecting another line with such calling line and when the operator wishes to do this she depresses the selected key 39 until the trip 12 is engaged by the cam 13 thereby to maintain the contacts 42 and 38 open. When the parts are restored to normal by the operation of the magnets 63 and 64 which has been described, any key 39 that has been depressed will be restored to normal.

I also desirably provide listening keys 69, each individual to a line entering the exchange and mechanically independent of the link connector equipment which I have previously described. These individual keys are so interrelated that they cannot be manipulated to permit an operator to listen in on an established connection nor to permit an additional line to become connected with an established connection, this feature of my invention being of importance irrespective of the mechanism which is employed to connect telephone lines in conversation. These individual keys 69 are to be used in the event of an unexpected number of connections desired by way of the exchange and enables the operator to inform the subscribers that the facilities of the exchange cannot for the time being permit of connections desired. To prevent the operators from listening in upon an established connection and to prevent other lines from berelay T2 to permit its operation with the re- 7 sult de cribed. (ircuit establishable by each of the keys (it) through the relay T2 -may be traced from each ot the grounded batteries 73 through the resistance H. the then engaged contacts 7.1, the conductor 76, the magnet 77, the marginal relay 72 to ground. The magnet 72 is provided with an upper armature switch that serves when operated to actuate the signal 54 for the purpose previously described. The magnet 77 is energized when any key 9 is depressed for the purpose of removing the connections that intervene between the operators telephone 91 and the contacts 20, etc.. and serve to conneet said telephone 21 with the conductors and 71 with the operators telephone 21 and the normally open contacts of the listening keys 69 Each key (19 is provided with serially related contacts that are interposed between the lines and the link connectors so that when any key 69 is operated it will serve to prevent the operator from listening in upon established connections. Tz'tlking battery is furnished at T8 to the stations of local telephone lines and to the operator-s set 21 when a key (39 is depressed. The condensers T9 are included in the conductors TO and 71 between the key of the local lines and the keys of the trunk line to prevent the battery 78 from intertering with the signals at exchange 2. A high resi tance iinpwlanre coil 80 is included in bridge between the conductors i and T1 to enable the operat r to signal exchange and to prevent faulty operation of the signal apparatus at the trunk end of the iink circuit shown at 0x change 2.

If the operator should desire to restore the keys .3, t3 and i anuaily in may do so by mani latinn" the keys H. one such key bent; individual to :tttll ii k connector, the

t oi the irae'net 3. the position v'hz h let's may be moved being ind it d i' o whereatter esitired to lt t' i i flown and ar ny inv ntion lie pinch readily be made without departing from the spirit of my invention.

-llavin;: thus descri ed my invention I claim as no and desire to secure by Letters Patent the following:

1. A teleph ne xchange system including a plurality of telephone lincs extending to an exchange; plurality ot' link connectors for joining: said lines in telephonic connection; a plural ty of .-\\it 'l)es for each link connector, each switch being individual to a telephone line, tlltr-t switches having contacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are'common whereby line; may be telephonically connected: and an operators telephone provided with circuit connections governed by said switches and serving to enable the telephonic connect ion thereof with the telephone lines.

2. A telephone exchange system including a plurality of telephone lines extending to an exchange: a plurality of link connectors for joining said lines in telephonic connection; a plurality ot switches for each link connector each switch being indi\ idual to a telephone line, these switches having e011- tacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are common whereby lines may be telephonic; lly connected: an operat r s telephone provided with cirruit connections governed by said switches and sci-vine to enable the telephonic connwticn thereot with the telephone lines: and a irre ot' signah ing current provided with cir uit connec tions governed by said switches and serving to enable the connection thereof with the telephone lines.

3. A telephon ex hange system including a plurality oi tt-l phone lines extending to an exchange: a plurality ot' link conne t r in interchauneable relation to calling lines and in lllltl'tilitittf'i ii it relation to called lines t'or inning said lintw in telephonic ronneet ion: a plurality olo erator ontrolled \\it l;".- tor and iiniii idual t ea h liul; coir nertt'ri each wwit li brine liltllvltlllftl to and A, i; h a telephone line. ntacts and circuit them to c iuirct the indi idual nith the i they a e, i HtltiH/l! pluralit I Q evi'hannr: :1 pi in llltu'ii'liili individual to each lines and in interchangeable relation to called lines for joining said lines in telephonic connection; a plurality of operator controlled switches for and individual to each link connector, each switch being individual to and permanently associated with a telephone line, these switches having contacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are common whereby lines may be telephonically connected; and mechanical means jointly controlled by the switches that connect calling and called lines with the same link connector for mechanically preventing such operation of an additional switch associated with this link connector that would connect the telephone line to which this additional switch is individual with this link connector. I

5. A telephone exchange system includ ing a plurality of telephone lines extending to an exchange; a plurality of link connectors in interchangeable relation to calling lines and in interchangeable relation to called lines for joining said lines in telephonic connection; a plurality of switches for and individual toeach link connector, each switch being individual to and permanently associated with a telephone line,

these switches havin contacts and circuit connections that enab e them to connect the lines to which they are individual with the link connector to which they are common whereby lines may be telephonically connected; and means olntly controlled by switches that connect calling and called lines with the same link connector for preventing inclusion of the operators telephone in connection with the connected lines.

6. A telephone exchange system including a plurality of telephone lines extending to an exchange; a plurality of link connectors in interchangeable relation to calling lines and in interchangeable relation to called lines for joining said lines in telephonic connection; a plurality of switches for and link connector, each switch being individual to and permanently associated with a telephone line these switches having contacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are common wherebylines may be telephonically connected; and mechanical means jointly controlled by the switches that connect calling and called lines with the same link connector for mechanically preventing the inclusion of the operators telephone in connection with the connected lines.

7. A telephone exchange system including a plurality of telephone lines extending to an exchange; a plurality of link connectors for joining said lines in telephonic connection; a plurality of switches for each link connector, each switch being individual to a telephone line, these switches having contacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are common whereby lines may be telephonically connected; and means jointly controlled by switches of difi'erent link connectors for preventing the inclusion of the operators telephone in connection with con nected lines.

8. A telephone exchange system including a plurality of telephone lines extending to an exchange; a plurality of link connectors in interchangeable relation to calling lines and in interchangeable relation to called lines for joining said lines in telephonic connection; a plurality of switches for and individual to each link connector each switch being individual to and permanently associated with a telephone line, switches having contacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are common whereby lines may be telephonically connected; and means jointly controlled by switches associated with the same link connector for preventinginclusion of the operators telephone in connection with connected lines.

9. A telephone exchange system including a-plurality of telephone lines extending to an exchange; a plurality of link connectors for joining said lines in telephonic connection; a plurality of switches for each link connector, each switch being individual to a telephone line, these switches having contacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are common whereby lines may be telephonically connected; and means jointly controlled by the switches of different link connectors for preventing the connection of a telephone linewith connected lines.

10. A telephone exchange system including a plurality of telephone lines extending to an exchange; a pluralityof link connectors in interchangeable relation to calling lines and vin interchangeable relation to called lines for joining said lines in telephonic connection; a plurality of operator controlled switches for and individual to each link connector, each switch being individual to and permanently associated with a telephone line, these switches having contacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are common whereby lines may be telephonicallyconnected; and means jointly controlled by the switches associated with the these a ing lines and in interchangeable relation to called lines for joining said lines in telephonic connection; a plurality of switches for and individual to each link connector, each switch being individual to and permanently associated with a telephone line, these switches having contacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are common whereby lines may be telephonically connected; means jointly controlled by the switches of calling and called parties for excluding the operators telephone from circuit; and switches for excluding calling lines from circuit relation with the operators telephone.

19. A telephone exchange system including a plurality of telephone lines extending to an exchange; a plurality of link connectors in interchangeable relation to calling lines and in interchangeable relation to called lines for joining said lines in telephonic connection: a plurality of switches for and individual to each link connector, each switch being individual to and permanently' associated with a telephone line, these switches having contacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are common whereby lines may be telephonically connected; switching mechanism for each link connector for 'includin the operators telephone in circuit relation with calling lines; and means governed by the switches of the calling and called lines for operating the switching mechanism two steps, the first step being eiiected by the switch of a calling line to include the operators telephone in circuit and the second step being effected by the switch of the called line to exclude the operators telephone from circuit.

20. A telephone exchange system including a plurality of telephone lines extending .to an exchange; a plurality of link connectors in interchangeable relation to calling lines and in interchangeable relation to called lines for joining said lines in telephonic connection; a plurality of switches for and individual to each link connector, each switch being individual to and perma nently associated with a telephone line, these switches having contacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are common whereby lines may be telephonically connected; and an operators telephone provided with circuit connections governed by said switches and serving to enable the telephonic connection thereof with the telephone lines.

21. A telephone exchange system including a plurality of telephone lines extending to an exchange; a plurality of link con- -governed by said switches and serving to enable the telephonic connection thereof with the telephone lines; and a source of signaling current provided with circuit connections governed by said switches which serve to enable the connection thereof with the telephone lines.

22. A telephone exchange system including a plurality of telephone lines extending to an exchange; a plurality of link connectors for joining said lines in telephonic connection; a plurality of switches for each link connector, each switch being individual to and permanently associated with a telephone line, these switches having contacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are common whereby lines may be telephonically connected; and means jointly con trolled by switches of different link connectors for preventing the inclusion of the operators telephone in connection with connected lines.

23. A telephone exchange system including a plurality of telephone lines extending to an exchange; a plurality of link connectors for joining lines in telephonic connection; a plurality of switches for each link connector, each switch being individual to and permanently associated with a telephone line, these switches having contacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are common whereby lines may be telephonically connected; and means jointly controlled by the switches of different link connectors for preventing the connection of a,

telephone line with connected lines.

24. A telephone exchange system including a plurality of telephone lines extending to an exchange; means for connecting these lines for conversation; operators listening switches individual to and permanently associated with the lines; and means jointly controlled by a plurality of listening switches forletfectively excluding the operators telephone from circuit with connected lines.

25. A telephone exchange system includ ing a plurality of telephone lines extending toan exchange; means for connecting these lines for conversation; operators listening switches individual to and permanently associated with the lines; and means jointly controlled by a plurality of listening switches for'ettectively excluding an additional telephone line from connection with connected lines.

26. A telephone exchange system including a plurality of telephone lines extend ing from subscribers stations to an ex change; a plurality of link connectors in interchangeable relation to calling lines and in interchangeable relation to called lines for joining said lines in telephonic connection; a plurality of switches for and individual to each link connector, each switch being: individual to and permanently associated with a telephone line, these switches having contacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are common whereby lines may be telephonically connected; and subscriber station controlled means for restoring actuated switches to normal.

27. A telephone exchange system including a plurality of telephone lines extending from subscribers stations to an exchange; a plurality of link connectors in interchangeable relation to calling lines and in interchangeable relation to called lines for joining said lines in telephonic connection a plurality of switches for and individual to each link connector, each switch being individual to a telephone line, these switches having con tacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are common whereby lines may be telephonically connected; and subscriber station controlled means for restoring actuated switches to normal.

A telephone exchange system including a plurality of telephone lines extending to an exchange; a plurality of link connectors for joiniln said lines in telephonic connection; a plurality of keys for each link connector each key being individual to a telephone line, these keys having contacts and circuit connections that enable them to connect the lines to which they are individual with the link connector to which they are common. whereby lines may be telephonically connected; an operators telephone; a plurality of operators keys for interchangeably associating the operators telephone with link connectors; means for holding said operators keys in actuated po sitions; and means common to and ix actuating relation with the aforesaid means, the operator's keys operating upon the first aforesaid means to operate the second aforesaid means whereby an operator's key in being depressed will ettectthe restoration of a previously depressed operator-s key.

In witness whereof, I hereunto subscribe my name this 24th day of July, A. D. 1911.

MORTON L. JOHNSON.

\l'itnesscs:

E. L. Burn, (l. L. CRAGG. 

